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Numéro de publicationUS4924699 A
Type de publicationOctroi
Numéro de demandeUS 07/106,664
Date de publication15 mai 1990
Date de dépôt13 oct. 1987
Date de priorité13 oct. 1986
État de paiement des fraisPayé
Autre référence de publicationDE3750323D1, DE3750323T2, EP0264756A2, EP0264756A3, EP0264756B1
Numéro de publication07106664, 106664, US 4924699 A, US 4924699A, US-A-4924699, US4924699 A, US4924699A
InventeursHiroshi Kuroda, Nobuo Kurihara, Shinichi Sakamoto
Cessionnaire d'origineHitachi, Ltd.
Exporter la citationBiBTeX, EndNote, RefMan
Liens externes: USPTO, Cession USPTO, Espacenet
Position measuring method using a satellite
US 4924699 A
Résumé
A method position measurement in which position about satellite orbits and information about time are received from satellites to determine a position of a point. The method includes a step to calculate a direction in which an error occurs based on positional information of a satellite and a step to determine the position of the point by use of road map information in the direction of the error.
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We claim:
1. A method for position measurement in a system having a plurality of satellite wherein said position measurement is performed using positional information of each satellite which includes information of an orbital path of said satellite and information of time elapsed between transmitting a signal from said satellite and receiving said signal at a point a position of which is to be measured, said method comprising the steps of:
calculating a direction in which an error occurs in position measurement for said satellite using positional information of said satellite; and
determining said position of said point by using road map information in said direction of said error.
2. A method according to claim 1 further comprising the steps of:
judging whether a result of determining said position of said point is an appropriate position on a map;
calculating a second direction in which a second error from occurs in position measurement for an arrangement of satellite using positional information of said arrangement of satellite when said result is not an appropriate position on said map; and
drawing a line extending in said second direction of said second error and passing through said position of said point determined by said determining step so as to attain an appropriate position on said line as an appropriate position of said point.
3. A method for position measurement in a system having a plurality of satellites wherein said position measurement is performed using positional information of a satellite which includes information of an orbital path of said satellite and information of time elapsed between transmitting a signal from said satellite and receiving said signal at a point a position of which is to be measured, said method comprising the steps of:
calculating a direction in which an error occurs in position measurement for a combination of satellites using positional information of said combination of satellites;
calculating a direction in which another error occurs in position measurement for another combination of satellites using positional information of said other combination of satellites; and
determining a position of a point from an intersection of lines representing said error and said other error respectively, each line extending in the direction in which said errors occur.
4. A method for position measurement in a system having a plurality of satellites wherein said position measurement is performed using positional information of each satellite which includes information of an orbital path of said satellite and information of time elapsed between transmitting a signal from said satellite and receiving said signal at a point a position of which is to be measured, said method comprising the steps of:
calculating said position of said point based on positional information from said satellites;
judging whether said position of said point is on a road of a map;
calculating a direction (O), a fluctuation from an arrangement of satellites using positional information of said arrangement of satellites when said position of said point is not on a road;
drawing a line having a gradient equal to the fluctuation direction (O) and passing through said position of said point calculated by said calculating step;
attaining an intersection between a line through passing a position of a point indicated by a result of the last position measurement and a position of a point indicated by a result of the second to the last position measurement; and
outputting as an appropriate position of said point position which exists on a road and is nearest to said intersection.
Description
BACKGROUND OF THE INVENTION

The present invention relates to a position measuring method for measuring one's position by use of a radio wave from a satellite.

A system for measuring position by use of a radio wave from a satellite has been described, for example, in the JP-A-58-30615. The position measuring system using a radio wave from a satellite is referred to as a GPS system herebelow. In this system, a position in a plane, namely, azimuth on the surface of the earth can be measured by use of three satellites. When using four satellites, not only measurement in a plane (for the latitude and the longitude) but also measurement of height (above the sea level) can be effected.

In the GPS system, since the measurement is accomplished by use of satellites, the precision thereof is determined by the positions of the satellites. When the satellites to be used are located at positions relatively near to the position to be measured or conditions which permit the receipt of radio waves is disturbed, the accuracy of the measurement is lowered.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a position measuring method in a GPS system in which error in the measurement can be reduced and the deterioration of the measuring accuracy can be prevented.

According to the present invention, there is provided a position measuring method in a GPS system in which a direction where a great error results in the GPS system, namely, a direction of the fluctuation in a result of a position measurement is calculated from positions of satellites and the error in the direction of the fluctuation is corrected by use of an intersection between the fluctuation direction and a direction of a fluctuation attained from another map information or from combination with another satellite.

When satellites are located at unfavorable locations or the condition to receive radio waves therefrom is disturbed, the direction where the error takes place is determined depending on the arrangement of satellites from which radio waves can be received. If a correction with respect to the direction of the error can be achieved by use of other information, for example, information from a map, the error can be reduced and hence the measuring accuracy is improved. In addition to the correction of the error by use of map information, the error can also be corrected by combining the satellite with another satellite.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic diagram showing the principle of position measurement in a GPS system;

FIG. 2 is a diagram schematically illustrating the relationships between satellite positions and directions of errors appearing in the results of the measurement;

FIG. 3; is a flowchart illustrating an operation to attain a direction of the error;

FIG. 4 is a schematic diagram showing a method to correct the error of the position measurement by use of map information;

FIG. 5 is a flowchart depicting a method to correct the error of the position measurement by use of map information;

FIG. 6 is a diagram schematically showing a method to correct the error in the position measurement by combining the satellite with another satellite;

FIG. 7 is a flowchart illustrating an operation to accomplish the correction of FIG. 6; and

FIG. 8 is a graph showing the relationships of the direction of the fluctuation between the actual measurement and the calculated results and those between the error of the position measurement and the error indices determined by the arrangement of the satellite.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, an embodiment of the present invention will be described. FIG. 1 is a schematic diagram showing the principle of the position measurement in the GPS system including satellites 1-4 used in the GPS system and a measuring position 5. In this system, positions of the satellites are calculated from data sent from the satellites, the data concerning orbits of the satellites; furthermore, the period of time necessary for the radio wave to travel from the satellite to the measuring position is measured for each satellite so as to attain a distance from the satellite to the measuring position, thereby solving a system of equations of position measurement to obtain the measuring position. It has been found in this situation that the error in the position measurement is closely related to the arrangement of the satellites. According to the calculated results, for a favorable arrangement of the satellite, the absolute error of the position measurement is about 30 m; whereas for an unfavorable arrangement of the satellites, the absolute error of the position measurement is at least 200 meters (m). However, the fluctuation of the measured results in a case of an unfavorable arrangement of the satellite, namely, the error of the position measurement is found to be attended with an orientation determined by the satellite arrangement.

FIG. 2 shows an arrangement of the satellites in which reference numerals 6-8 each indicate satellite positions. In this diagram, the outer-most circle represents an angle of elevation 0 and the center of the circle is the zenith. The direction of the fluctuation θ can be calculated from the satellite arrangement. FIG. 3 is a flowchart showing the calculation method of the fluctuation direction θ. Although FIG. 2 illustrates a case where a 2-dimensional position measurement is achieved by use of three satellites, the calculation method similarly applies to a case where a 3-dimensional position measurement is effected by use of four satellites.

Computation of the direction of the fluctuation (i.e. the direction of the error) is achieved according to the flowchart of FIG. 3. First, in step 100, the positions of the satellites are calculated. The method of the position calculation has already been known. Next, a unit vector from the measuring position to the satellite is calculated for each satellite in step 101. It is assumed here that an x axis, a y axis, and a z axis are respectively drawn in the directions to the east, north, and zenith viewed from the own position. Step 102 obtains a matrix-G, which is then used in step 103 to calculate a covariance matrix P. Step 104 calculates the fluctuation direction θ from the elements of the covariance matrix P. Although FIG. 3 shows a case where four satellites are used, if a 2-dimensional position measurement is accomplished with three satellites, the matrix G of the step 102 becomes ##EQU1## and the fluctuation direction θ is calculated through the steps 103-104.

FIG. 4 shows a method to correct measured results by use of the fluctuation direction and road map information, whereas FIG. 5 is a flowchart of the correction method. Assume that the result of computation of the position measurement indicates point 14 in step 200. Step 201 judges whether or not the point 14 is on a road. Incidentally, reference numerals 9-10 represent roads in FIG. 4.

If the point 14 is not on the road, step 100 is executed to attain the fluctuation direction θ. In FIG. 4, the figure enclosed with a dotted line 11 indicates a distribution of the measured results. In step 202, a direct line 12 having a direction θ is drawn to pass the point 14. When this direct line 12 has an intersection with respect to a road, the intersection is regarded as the measuring position. However, since the direct line 12 generally intersects a plurality of roads, a direct line 13 is drawn to pass the points 15 and 16 representing the results of the last measurement and the second to the last measurement, respectively. Step 204 then attains an intersection 17 between the direct lines 12 and 13. In step 205, a point 18 on the direct line 12 and nearest to the point&17 is recognized to be the measuring position, and then step 206 displays the point 18 as the measuring position.

FIG. 6 shows a method in which the position measurement is achieved by use of two satellites and the measurement results are corrected depending on the combination of the satellites; whereas FIG. 7 is a flowchart illustrating the operation of the method. Step 301 selects a combination of two satellites and then step 302 effects the respective operations for the position measurement so as to attain points 19-20 as results of the point measurements. In the routine 100, the fluctuation directions θ1 and θ2 are attained from locations of the satellites 1-2 of the combination. Dotted lines 23-24 respectively indicate distributions of the results of the position measurements. In step 303, two direct lines 21-22 respectively having the fluctuation directions are drawn to pass the results of the position measurements. Step 304 obtains an intersection 25 of the two direct lines 21-22 as the measuring position.

FIG. 8 is a graph showing relationships of the fluctuation direction between the measured values and the calculated values and those between the errors of the position measurements and the error indices determined by the satellite arrangement. The estimated values of the fluctuation direction θ substantially agree with the measured values thereof for the error index equal to or greater than ten, which enables to confirm that the fluctuation angle θ is appropriately specified. Incidentally, the errors of the position measurements are indicated by the values before the correction in this graph. The error index is substantially proportional to the measurement error and the error of the position measurement is at least 200 m when the error index is at least 30. When the correction method according to the present invention is applied to the results of the position measurement, the error of the position measurement after the correction can be reduced to about 50 m as indicated by the shaded area in FIG. 8.

According to the present invention, in a case where the measuring position is determined by use of the GPS system, the fluctuation directions of the results of the position measurements can be estimated beforehand from the arrangement of satellites so as to correct the results of the position measurements, which loads to an effect that the absolute error of the measuring position thus attained car be minimized.

While the present invention has been described with reference to the particular embodiment, it is not restricted by the embodiment but only by the appended claims. It is to be appreciated that those skilled in the art can change and modify the embodiment without departing from the scope and spirit of the invention.

Citations de brevets
Brevet cité Date de dépôt Date de publication Déposant Titre
US4677450 *14 mars 198530 juin 1987Mitsubishi Denki Kabushiki KaishaAutomotive navigation system
US4677561 *24 avr. 198530 juin 1987Mitsubishi Denki Kabushiki KaishaAutomotive navigation system
US4677562 *10 mai 198530 juin 1987Mitsubishi Denki Kabushiki KaishaAutomotive navigation system
US4677563 *22 avr. 198530 juin 1987Mitsubishi Denki Kabushiki KaishaAutomotive navigation system
Référencé par
Brevet citant Date de dépôt Date de publication Déposant Titre
US5274840 *28 oct. 199128 déc. 1993Motorola, Inc.Satellite communication system
US5299130 *1 mai 198929 mars 1994Toyoichi OnoApparatus for controlling movement of vehicle
US5323152 *9 avr. 199321 juin 1994Sumitomo Electric Industries, Ltd.Apparatus for detecting the position of a vehicle
US5375059 *18 févr. 199320 déc. 1994Caterpillar Inc.Vehicle position determination system and method
US5390125 *18 févr. 199314 févr. 1995Caterpillar Inc.Vehicle position determination system and method
US5442558 *6 août 199215 août 1995Caterpillar Inc.Method and system for determining vehicle position based on a projected position of a satellite
US5465289 *5 mars 19937 nov. 1995E-Systems, Inc.Cellular based traffic sensor system
US5493294 *4 janv. 199520 févr. 1996Sumitomo Electric Industries, Ltd.Apparatus for detecting the position of a vehicle
US5512902 *18 avr. 199430 avr. 1996Northrop Grumman CorporationStock locator system using GPS translator
US5555503 *23 nov. 199310 sept. 1996Caterpillar Inc.System and method for providing accurate vehicle positioning using spatial bias techniques
US5557254 *16 nov. 199317 sept. 1996Mobile Security Communications, Inc.Programmable vehicle monitoring and security system having multiple access verification devices
US5587715 *19 mars 199324 déc. 1996Gps Mobile, Inc.Method and apparatus for tracking a moving object
US5629855 *1 juin 199513 mai 1997Caterpillar Inc.System and method for using parabolic models to improve position estimates from a global positioning system
US5796365 *23 déc. 199618 août 1998Lewis; Peter T.Method and apparatus for tracking a moving object
US6046687 *10 mars 19974 avr. 2000Trimble Navigation LimitedClandsetine location reporting for missing vehicles
US63734035 nov. 199916 avr. 2002Kelvin KorverApparatus and method for improving the safety of railroad systems
US666210128 janv. 20029 déc. 2003Matsushita Electric Industrial Co., Ltd.Method and apparatus for transmitting position information on a digital map
US669775219 mai 200024 févr. 2004K&L Technologies, Inc.System, apparatus and method for testing navigation or guidance equipment
US692039225 avr. 200219 juil. 2005Matsushita Electric Industrial Co., Ltd.Digital map position transfer method
US69313197 déc. 200116 août 2005Matsushita Electric Industrial Co., Ltd.Method for transmitting information on position on digital map and device used for the same
US733366626 avr. 200219 févr. 2008Matsushita Electric Industrial Co., Ltd.Digital map shape vector encoding method and position information transfer method
US735310829 août 20031 avr. 2008Matsushita Electric Industrial Co., Ltd.Method and apparatus for transmitting position information on a digital map
US753934811 oct. 200726 mai 2009Panasonic CorporationDigital map shape vector encoding method and position information transfer method
US763445214 févr. 200215 déc. 2009Panasonic CorporationMethod for locating road shapes using erroneous map data
US773784114 juil. 200615 juin 2010RemotemdxAlarm and alarm management system for remote tracking devices
US78044128 févr. 200828 sept. 2010Securealert, Inc.Remote tracking and communication device
US793626214 juil. 20063 mai 2011Securealert, Inc.Remote tracking system with a dedicated monitoring center
US80137362 juin 20106 sept. 2011Securealert, Inc.Alarm and alarm management system for remote tracking devices
US80310773 sept. 20104 oct. 2011Securealert, Inc.Remote tracking and communication device
US807856324 nov. 200913 déc. 2011Panasonic CorporationMethod for locating road shapes using erroneous map data
US808640120 mai 200527 déc. 2011Panasonic CorporationMethod for transmitting information on position on digital map and device used for the same
US81853065 févr. 200822 mai 2012Panasonic CorporationMethod and apparatus for transmitting position information on a digital map
US821931428 avr. 200810 juil. 2012Panasonic CorporationMethod for transmitting location information on a digital map, apparatus for implementing the method and traffic information provision/reception system
US82328766 mars 200931 juil. 2012Securealert, Inc.System and method for monitoring individuals using a beacon and intelligent remote tracking device
US83699677 mars 20115 févr. 2013Hoffberg Steven MAlarm system controller and a method for controlling an alarm system
US837005424 mars 20055 févr. 2013Google Inc.User location driven identification of service vehicles
US851407018 juin 201020 août 2013Securealert, Inc.Tracking device incorporating enhanced security mounting strap
US865558023 nov. 201118 févr. 2014Panasonic CorporationMethod for transmitting information on position on digital map and device used for the same
US879721014 juil. 20065 août 2014Securealert, Inc.Remote tracking device and a system and method for two-way voice communication between the device and a monitoring center
US883838630 déc. 200916 sept. 2014Panasonic Intellectual Property Corporation Of AmericaMethod for transmitting location information on a digital map, apparatus for implementing the method, and traffic information provision/reception system
US88924958 janv. 201318 nov. 2014Blanding Hovenweep, LlcAdaptive pattern recognition based controller apparatus and method and human-interface therefore
US912950417 juin 20148 sept. 2015Securealert, Inc.Tracking device incorporating cuff with cut resistant materials
US915163324 mars 20146 oct. 2015Steven M. HoffbergMobile communication device for delivering targeted advertisements
US917748712 mars 20073 nov. 2015Panasonic Intellectual Property Corporation Of AmericaDigital map position information transfer method
US953556312 nov. 20133 janv. 2017Blanding Hovenweep, LlcInternet appliance system and method
US95515825 oct. 201524 janv. 2017Blanding Hovenweep, LlcMobile communication device
US20030078720 *7 déc. 200124 avr. 2003Shinya AdachiMethod for transmitting information on position on digital map and device used for the same
US20030093221 *26 avr. 200215 mai 2003Shinya AdachiDigital map shape vector encoding method and position information transfer method
US20030154019 *14 févr. 200214 août 2003Matsushita Electric Industrial Co., Ltd.Method for transmitting location information on a digital map
US20040039524 *29 août 200326 févr. 2004Matsushita Electric Industrial Co., LtdMethod and apparatus for transmitting position information on a digital map
US20050131632 *8 déc. 200416 juin 2005Matsushita Electric Industrial Co., Ltd.Digital map position information transfer method
US20050216189 *20 mai 200529 sept. 2005Matsushita Electric Industrial Co., Ltd.Method for transmitting information on position on digital map and device used for the same
US20060217885 *24 mars 200528 sept. 2006Mark CradyUser location driven identification of service vehicles
US20070150181 *12 mars 200728 juin 2007Matsushita Electric Industrial Co., Ltd.Digital map position information transfer method
US20080201073 *28 avr. 200821 août 2008Matsushita Electric Industrial Co., Ltd.Method for transmitting location information on a digital map, apparatus for implementing the method and traffic information provision/reception system
US20100070170 *24 nov. 200918 mars 2010Panasonic CorporationMethod for locating road shapes using erroneous map data
US20100106410 *30 déc. 200929 avr. 2010Panasonic CorporationMethod for transmitting location information on a digital map, apparatus for implementing the method, and traffic information provision/reception system
Classifications
Classification aux États-Unis73/178.00R, 340/990, 701/454, 701/470, 701/469
Classification internationaleG01C21/00, G01S19/50, G01S19/28
Classification coopérativeG01S19/50
Classification européenneG01S19/50
Événements juridiques
DateCodeÉvénementDescription
13 oct. 1987ASAssignment
Owner name: HITACHI, LTD., JAPAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:KURODA, HIROSHI;KURIHARA, NOBUO;SAKAMOTO, SHINICHI;REEL/FRAME:005207/0938
Effective date: 19871002
30 sept. 1993FPAYFee payment
Year of fee payment: 4
26 sept. 1997FPAYFee payment
Year of fee payment: 8
26 sept. 2001FPAYFee payment
Year of fee payment: 12